title: Bacillus thuringiensis colonises plant roots in a phylogeny-dependent manner.
abstract: Although much is known about the pathology of Bacillus thuringiensis against invertebrates, current understanding of its natural ecology is limited. This study evaluated the biodiversity of B. thuringiensis in relation to its interaction with plants. Phylogenetic relationships between 44 reference and field-collected strains, determined using 16S rRNA and gyrB gene sequences, revealed a high degree of variability, similar to that found in databases. An Arabidopsis thaliana in vitro inoculation model was developed to screen the ability of B. thuringiensis to colonise roots. Significant colonisation differences up to 91-fold were observed between strains, and correlation between strain phylogeny and colonisation was found. The genetics and biochemistry of auxin production; presence of the gene encoding indole pyruvate decarboxylase; and the abilities of Bt strains to swarm, grow in rich/minimal media and affect root growth differed between the strains, but only auxin production correlated significantly with ability to colonise roots. Co-inoculation with Burkholderia phytofirmans PsJN or Pseudomonas fluorescens SBW25 produced no effect on B. thuringiensis colonisation levels, regardless of the co-inoculant. Similarly, root colonisation of A. thaliana mutants impaired in plant defences was not significantly higher compared with controls. This is the first systematic and phylogenetic evaluation of B. thuringiensis interaction with plants.
authors.affiliation: Cardiff School of Biosciences, Cardiff University, Cardiff, UK.
authors.forename: J Cristian
authors.initials: JC
authors.lastname: Vidal-Quist
authors.forename: Hilary J
authors.initials: HJ
authors.lastname: Rogers
authors.forename: Eshwar
authors.initials: E
authors.lastname: Mahenthiralingam
authors.forename: Colin
authors.initials: C
authors.lastname: Berry
mesh_terms: D017360:Arabidopsis / Q000276:immunology / Q000382:microbiology* / Q000502:physiology; D001413:Bacillus thuringiensis / Q000145:classification* / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D019117:Burkholderia / Q000254:growth & development; D002262:Carboxy-Lyases / Q000235:genetics; D027081:DNA Gyrase / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D007210:Indoleacetic Acids / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D018517:Plant Roots / Q000382:microbiology*; D011551:Pseudomonas fluorescens / Q000254:growth & development; D012336:RNA, Ribosomal, 16S / Q000235:genetics
chemical_list: D004269:DNA, Bacterial; D007210:Indoleacetic Acids; D012336:RNA, Ribosomal, 16S; C068832:indolepyruvate decarboxylase; D002262:Carboxy-Lyases; D027081:DNA Gyrase
keywords: Arabidopsis thaliana; colonisation; endophyte; gyrB; inoculation; rhizobacteria